1. Field of the Invention
The present invention relates to a method of manufacturing a radiating plate and a semiconductor apparatus using the radiating plate.
2. Description of the Related Art
In a semiconductor apparatus mounting a semiconductor device by a flip chip connection, a radiating plate is attached to the back surface of the semiconductor device (a surface on an opposite side to the flip chip connecting surface of the semiconductor device) to enhance the thermal radiating property thereof. FIG. 7 shows an example of a semiconductor apparatus formed by flip chip connecting a semiconductor device 12 to a substrate 10 with bonding a radiating plate 14 to the back surface of the semiconductor device 12. In this example, the radiating plate 14 is provided with a housing concave portion 14a for accommodating the semiconductor device 12 and the semiconductor device 12 is bonded to the inner bottom surface (or ceiling surface) of the housing concave portion 14a, and furthermore, the radiating plate 14 is bonded to the substrate 10 to surround a region on which the semiconductor device 12 is mounted.
In FIG. 7, the radiating plate 14 is formed in a cap-shape to protect the semiconductor device 12 and to enhance the thermal radiating function of the semiconductor device 12. Various configurations might be used for the radiating plate 14, for example, a radiating plate with radiating fin being provided.
The radiating plate which might be employed in this invention includes so called heat-sink, heat-slug, heat-spreader and so on.
In the case in which the radiating plate 14 is attached to the semiconductor device 12, a thermal conductor such as a solder or a high-temperature conducting resin, such as epoxy resin, is interposed between the semiconductor device 12 and the radiating plate 14 for their assembling in order to enhance a thermal conductivity between the semiconductor device 12 and the radiating plate 14. In some cases such that the thermal conductor is provided between the semiconductor device 12 and the radiating plate 14, the thermal conductor is interposed between the semiconductor device 12 and the radiating plate 14 where pressure contact is performed to assemble them. In general, however, heat treatment might be performed to the solder or the high-temperature conducting resin rather than pressure contact so that the thermal conductor fills clearance between the back surface of the semiconductor device 12 and the radiating plate 14, which ends up being bonded integrally with each other.
If the thermal conductor is heated and molten to bond the semiconductor device 12 to the radiating plate 14 with high temperature, however, there is a possibility of causing a great thermal stress between the substrate 10 and the semiconductor device 12, as well as between the radiating plate 14 and the semiconductor device 12, resulting in the damage of the semiconductor device 12. As in the case in which the solder is used as the thermal conductor, moreover, if the thermal conductor is molten to bond the semiconductor device 12 to the radiating plate 14, there is a problem of the generated voids remaining between the back surface of the semiconductor device 12 and the radiating plate 14, which does not fill up the clearance portion completely, resulting in tampering a thermal conductivity in some cases. On the other hand, in the case in which the high-temperature conducting resin is used as the thermal conductor, giving the priority to good filling condition of the thermal conductor, there is a problem of the thermal conductivity turning to be lower in comparison of a metal material such as the solder.